US drugs giant Pfizer faces a grilling in the US over its £63bn AstraZeneca bid

Drugs giant Pfizer will face a grilling today from US shareholders and analysts over its £63billion takeover bid for Britain’s AstraZeneca as it unveils its results for the first three months of this year.

Chief executive Ian Read is likely to face brickbats from politicians in America over the bid, which is aimed at moving Pfizer’s tax domicile to the UK.

John Koskinen, commissioner of the Internal Revenue Service, said the US Government is probably unable to take action to stop companies doing deals to move their tax address outside the country – a practice known as ‘reflagging.’

Pfizer: The company hopes to pay 21 per cent on earnings in Britain compared with 38 per cent in the US

Pfizer’s bid is the biggest in a line of tax-minimising deals by US companies, including banana giant Chiquita, which took over Irish group Fyffes and is moving its tax jurisdiction to Eire.

The Astra transaction, which will potentially deprive the US state coffers of billions of dollars at a time when budgets are crunched, will lead to fresh calls in Washington to tighten up the tax rules.

Senator Bernie Sanders of Vermont has placed Pfizer on a list of ‘Top Ten Corporate Tax Avoiders,’ claiming it paid no income taxes from 2010 to 2012 and that it received $2.2billion of tax refunds from the IRS at the same time as making $43billion in worldwide profit.

Pfizer increased the amount it spends on lobbying by $1million to $3.19million in the first quarter of this year, according to US reports.

Scots born Read, 59, who was paid $17.7million (£10.5million) last year, jetted into the UK last week to woo British politicians and investors.

His strategy is to conduct a ‘bear-hug’ attack on Astra by lobbying shareholders in order to force its management, who rebuffed his latest offer, into agreeing to talks.

Read won support from shareholders Schroders and Axa, but failed to convince leading fund manager Neil Woodford of Woodford Investment Management.

On Friday, Read raised his bid to £50 a share, but Woodford, the biggest name in British fund management, backed the view of the Astra board that this still undervalues the company.

Woodford, who previously worked at asset management group Invesco, was instrumental in ousting former Astra boss David Brennan. He also opposed the failed bid for BAE Systems by European aerospace conglomerate EADS.

Although not such a large shareholder in Astra at his new firm, his views will be extremely influential.

‘I have a vision of how the sector could deliver more value for shareholders,’ he told a Sunday newspaper.

The political row over Astra’s fate – and that of its 7,000 employees in Britain – is also heating up as Labour leader Ed Miliband accused David Cameron of acting as a ‘cheerleader’ for the deal.

Last night, a Pfizer spokesman said: ‘We comply with tax and accounting laws and pay our fair share of taxes wherever we do business.’